day23, part1

day23/paths.go

@@ -0,0 +1,57 @@
+package day23
+
+import (
+	mapset "github.com/deckarep/golang-set/v2"
+)
+
+type PathEnd struct {
+	end     Coord
+	visited mapset.Set[Coord]
+}
+
+func ExtendPath(p PathEnd, f Field) (nextPaths []PathEnd) {
+	endPointNeighbors := f.Neighbors(p.end)
+	for _, potentialNewEnd := range endPointNeighbors {
+		if !p.visited.Contains(potentialNewEnd) {
+			nextVisited := p.visited.Clone()
+			nextVisited.Add(p.end)
+			nextPaths = append(nextPaths, PathEnd{
+				end:     potentialNewEnd,
+				visited: nextVisited,
+			})
+		}
+	}
+
+	return
+}
+
+// return paths that end on End
+func RunAllScenicPaths(f Field) (result []PathEnd) {
+	pathsToFurther := []PathEnd{
+		{end: Coord{Row: 0, Col: f.StartCol}, visited: mapset.NewSet[Coord]()},
+	}
+
+	theEndCoord := Coord{Row: f.MaxRow, Col: f.EndCol}
+
+	for len(pathsToFurther) > 0 {
+		curCheckedPath := pathsToFurther[0]
+		pathsToFurther = pathsToFurther[1:]
+
+		if curCheckedPath.end == theEndCoord {
+			result = append(result, curCheckedPath)
+			continue
+		}
+
+		nextSteps := ExtendPath(curCheckedPath, f)
+
+		// log.Printf("for %+v next steps %+v\n", curCheckedPath, pathsToFurther)
+		// log.Printf("remaining paths to check len is %d", len(pathsToFurther))
+		// log.Println(pathsToFurther)
+
+		if len(nextSteps) > 0 {
+			pathsToFurther = append(pathsToFurther, nextSteps...)
+		}
+	}
+
+	return
+}